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Publicações

2023

A Two-Stage Method for Polyp Detection in Colonoscopy Images Based on Saliency Object Extraction and Transformers

Autores
Lima, ACD; de Paiva, LF; Braz, G; de Almeida, JDS; Silva, AC; Coimbra, MT; de Paiva, AC;

Publicação
IEEE ACCESS

Abstract
The gastrointestinal tract is responsible for the entire digestive process. Several diseases, including colorectal cancer, can affect this pathway. Among the deadliest cancers, colorectal cancer is the second most common. It arises from benign tumors in the colon, rectum, and anus. These benign tumors, known as colorectal polyps, can be diagnosed and removed during colonoscopy. Early detection is essential to reduce the risk of cancer. However, approximately 28% of polyps are lost during this examination, mainly because of limitations in diagnostic techniques and image analysis methods. In recent years, computer-aided detection techniques for these lesions have been developed to improve detection quality during periodic examinations. We proposed an automatic method for polyp detection using colonoscopy images. This study presents a two-stage polyp detection method for colonoscopy images using transformers. In the first stage, a saliency map extraction model is supported by the extracted depth maps to identify possible polyp areas. The second stage of the method consists of detecting polyps in the extracted images resulting from the first stage, combined with the green and blue channels. Several experiments were performed using four public colonoscopy datasets. The best results obtained for the polyp detection task were satisfactory, reaching 91% Average Precision in the CVC-ClinicDB dataset, 92% Average Precision in the Kvasir-SEG dataset, and 84% Average Precision in the CVC-ColonDB dataset. This study demonstrates that polyp detection in colonoscopy images can be efficiently performed using a combination of depth maps, salient object-extracted maps, and transformers.

2023

CRIBA: A Tool for Comprehensive Analysis of Cryptographic Ransomware's I/O Behavior

Autores
Esteves, T; Pereira, B; Oliveira, RP; Marco, J; Paulo, J;

Publicação
2023 42ND INTERNATIONAL SYMPOSIUM ON RELIABLE DISTRIBUTED SYSTEMS, SRDS 2023

Abstract
Cryptographic ransomware attacks are constantly evolving by obfuscating their distinctive features (e.g., I/O patterns) to bypass detection mechanisms and to run unnoticed at infected servers. Thus, efficiently exploring the I/O behavior of ransomware families is crucial so that security analysts and engineers can better understand these and, with such knowledge, enhance existing detection methods. In this paper, we propose CRIBA, an open-source framework that simplifies the exploration, analysis, and comparison of I/O patterns for Linux cryptographic ransomware. Our solution combines the collection of comprehensive information about system calls issued by ransomware samples, with a customizable and automated analysis and visualization pipeline, including tailored correlation algorithms and visualizations. Our study, including 5 Linux ransomware families, shows that CRIBA provides comprehensive insights about the I/O patterns of these attacks while aiding in exploring common and differentiating traits across families.

2023

Policy gradients using variational quantum circuits

Autores
Sequeira, A; Santos, LP; Barbosa, LS;

Publicação
QUANTUM MACHINE INTELLIGENCE

Abstract
Variational quantum circuits are being used as versatile quantum machine learning models. Some empirical results exhibit an advantage in supervised and generative learning tasks. However, when applied to reinforcement learning, less is known. In this work, we considered a variational quantum circuit composed of a low-depth hardware-efficient ansatz as the parameterized policy of a reinforcement learning agent. We show that an epsilon-approximation of the policy gradient can be obtained using a logarithmic number of samples concerning the total number of parameters. We empirically verify that such quantum models behave similarly to typical classical neural networks used in standard benchmarking environments and quantum control, using only a fraction of the parameters. Moreover, we study the barren plateau phenomenon in quantum policy gradients using the Fisher information matrix spectrum.

2023

Depletion Based Digital and Analogue Circuits with n-Channel IGZO Thin Film Transistors

Autores
Carvalho, G; Pereira, M; Kiazadeh, A; Tavares, VG;

Publicação
2023 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS, ISCAS

Abstract
In this work, both analogue and digital depletionmode single channel transistor circuits are presented and are simulated using an n-channel IGZO technology with V-TH =-0.87V. A logic family is introduced, suppressing the need for an additional voltage level and level restoring circuitry. Furthermore, in the analogue domain, a depletion current mirror topology is presented with demonstrated small current error. Finally, the current mirror is used in the design of an OpAmp, achieving a simulated open-loop gain of 45 dB, CMRR of 58 dB, unity-gain frequency of 444 kHz and a phase margin of 71 degrees.

2023

Current devices and Future Perspectives on Neuromuscular Blockade Monitoring: A Systematic Review

Autores
Torneiro, A; Oliveira, E; Rodrigues, NF;

Publicação
2023 IEEE 11TH INTERNATIONAL CONFERENCE ON SERIOUS GAMES AND APPLICATIONS FOR HEALTH, SEGAH

Abstract
Postoperative residual neuromuscular block (PRNB) is still a problem during the surgery procedures resulting in health problems, such as, airway obstruction, hypoxia and pulmonary aspiration. To perform more accurate monitoring of the patient during surgery quantitative neuromuscular blockade monitoring measuring TOF ratio has been recommended by medical institutions. There are some devices available using different techniques, however there are only a few number of clinicians using them, since those devices are costly and have difficult clinical set-up. This paper presents a systematic review of current devices for quantitative neuromuscular monitoring during the surgery procedure following the PRISMA methodology. This study was carried out to list the currently available devices and report the capabilities that are missing in these devices since 2017. The databases used to do the research were PubMed, Cochrane Library, PubMed Central (PMC), Web of Science, IEEE Xplore, ScienceDirect, Directory of Open Access Journals (DOAJ). 17 articles were selected, presenting comparisons between two devices using different techniques. Quantitative monitoring provides the most accurate TOF ratio measurement but still needs to be incentivized.

2023

Zero-shot Classification at Different Levels of Granularity

Autores
Molina, M;

Publicação
2023 IEEE/CVF Conference on Computer Vision and Pattern Recognition Workshops (CVPRW)

Abstract

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